Katherine McPhee has returned to the "American Idol" stage.

The 37-year-old singer-actress was the runner-up of the singing competition's fifth season, losing to Taylor Hicks.

Now, she's returned to the show to perform with two of this season's contestants, Alyssa Wray and Willie Spence.

"Growing up, I would get in my mom's bed and watch 'American Idol' and I do remember when [McPhee] was on the show," Wray said in a package on the show. "I just thought she was this insane powerhouse."

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The two performed "I'm Your Baby Tonight" by Whitney Houston together -- though Wray, 19, wasn't terribly familiar with the song before their rehearsals.

"We're going to be singing 'I'm You Baby Tonight' by Whitney Houston, which I heard you didn't even really know which made me shed a tear because that's how young you are," joked the "Smash" actress.

The performance stunned the judges, who gushed over the pair.

"The two of you together, I'm telling you, complimented each other so well," said Lionel Richie. "... Together you made it look like you've been doing it for a hundred years."

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"I think you're the first singer that really held your own on stage with the other star," praised Katy Perry.

Spence kicked off his evening with a cover of Bette Midler's "Wind Beneath My Wings" before welcoming McPhee to the stage to perform Céline Dion and Andrea Bocelli's "The Prayer."

"One of the things that I think is really special about you and that I love about singers is their ability to make you feel like they're telling a story," McPhee said in their rehearsals.

The star dedicated her performance to her father, who passed away three years ago.

"I hope it's going to be as special to the audience as it is to us," she gushed.

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As was the case for McPhee's performance with Wray, the trio of judges had nothing but kind words to say about the duet.

McPhee has appeared a number of times on "American Idol" since coming in second place in 2006. According to IMDb, she appeared in the show's 7th, 15th and 18th seasons in addition to her Sunday night performance.

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Wray also performed a cover of "Something in the Water" by Carrie Underwood, yet another alum of the show's earlier days.